Re: [BUGFIX][PATCH] oom-kill: fix NUMA consraint check with nodemask v2

[KOSAKI Motohiro]

Hi

> ===================================================================
> --- mmotm-2.6.32-Nov2.orig/mm/oom_kill.c
> +++ mmotm-2.6.32-Nov2/mm/oom_kill.c
> @@ -196,27 +196,40 @@ unsigned long badness(struct task_struct
>  /*
>   * Determine the type of allocation constraint.
>   */
> +#ifdef CONFIG_NUMA
>  static inline enum oom_constraint constrained_alloc(struct zonelist *zonelist,
> -						    gfp_t gfp_mask)
> +				    gfp_t gfp_mask, nodemask_t *nodemask)
>  {
> -#ifdef CONFIG_NUMA
>  	struct zone *zone;
>  	struct zoneref *z;
>  	enum zone_type high_zoneidx = gfp_zone(gfp_mask);
> -	nodemask_t nodes = node_states[N_HIGH_MEMORY];
> +	int ret = CONSTRAINT_NONE;
>  
> -	for_each_zone_zonelist(zone, z, zonelist, high_zoneidx)
> -		if (cpuset_zone_allowed_softwall(zone, gfp_mask))
> -			node_clear(zone_to_nid(zone), nodes);
> -		else
> +	/*
> + 	 * The nodemask here is a nodemask passed to alloc_pages(). Now,
> + 	 * cpuset doesn't use this nodemask for its hardwall/softwall/hierarchy
> + 	 * feature. Then, only mempolicy use this nodemask.
> + 	 */
> +	if (nodemask && nodes_equal(*nodemask, node_states[N_HIGH_MEMORY]))
> +		ret = CONSTRAINT_MEMORY_POLICY;

!nodes_equal() ?


> +
> +	/* Check this allocation failure is caused by cpuset's wall function */
> +	for_each_zone_zonelist_nodemask(zone, z, zonelist,
> +			high_zoneidx, nodemask)
> +		if (!cpuset_zone_allowed_softwall(zone, gfp_mask))
>  			return CONSTRAINT_CPUSET;

If cpuset and MPOL_BIND are both used, Probably CONSTRAINT_MEMORY_POLICY is
better choice.



>  
> -	if (!nodes_empty(nodes))
> -		return CONSTRAINT_MEMORY_POLICY;
> -#endif
> +	/* __GFP_THISNODE never calls OOM.*/
>  
> +	return ret;
> +}
> +#else
> +static inline enum oom_constraint constrained_alloc(struct zonelist *zonelist,
> +				gfp_t gfp_mask, nodemask_t *nodemask)
> +{
>  	return CONSTRAINT_NONE;
>  }
> +#endif


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